05-25-10 CHASE LOG: CO/KS

This was a successful chase day in a Slight Risk area of southeast CO where we intercepted several supercell storms and saw an incredible tornado near Bartlett, CO.We had a long drive ahead of us already as we left Valentine, NE in the early morning and were targeting somewhere around Johnson City, KS.Our drive took us south on Hwy 83 through western KS and then west on Hwy 50 as a pair of supercells, one that had developed across southwest CO and another across the OK Panhandle.We originally decided to target the southern storm on the dryline, but the other storm was showing strong signs of rotation and close to crossing a stalled boundary around Hwy 96 to the north of Lamar.Upon reaching Johnson City, KS we went west on Hwy 116 and then north on Hwy’s 89 and 385 to near Sheridan Lake to intercept the storm that had already produced several landspout tornadoes.We did see a lowering and funnel upon approaching the storm, but it quickly weakened and became a big HP mess upon moving to the north of the boundary in the more stable air.

Our original targeted storm well to the south, which was now a tail end Charlie storm as others had filled in between, had been and continued to be tornado warned.This storm was only moving north-northeast at around 5 mph so it would be an easy intercept.We progressed south on Hwy 287 and then east on Hwy 116 to intercept this storm near Manter, KS.The supercell was still warned at this point and had unbelievable structure, while all the while having a big, rotating wall cloud underneath for around an hour.Another, beautiful LP storm was visible to the north and very photogenic.This supercell was barely moving at all so we were able to view from a close distance for over an hour before we decided that it was not going to do very much, plus it was looking rather high based with weak inflow winds.Wanting to see some of the large hail from this storm, we traveled south on Hwy 160 to near the small town of Bartlett, CO.Here we continued to watch the storm from the back and check out the ping pong ball and a few stones near baseball size that had fallen out of this storm earlier.After sitting for about 20 minutes, the storm started to have a lot of rising motion and then what appeared to be outflow on the southwest side.To our BIG surprise, the area of outflow started to have very fast and rotating rising motion and produced a funnel that quickly became a large cone tornado right in front of us!This was clearly not expected as the other vans had to be alerted to the oncoming tornado via radio and managed to get out just in time to view the tornado at a safe distance, but at very close range for around 3-4 minutes.Really, this was an unbelievable surprise to have this storm produce a tornado just before sunset, especially since it was not showing any signs of rotation before this tornado spun up.Clearly seemed like a “freak of nature” tornado more than anything and one that I will never forget.